Closed-cycle shallow geothermal energy exchange well and exchange system

Abstract

The utility model relates to a closed-cycle shallow geothermal energy exchange well and an exchange system. The technical problems that according to an existing hot dry rock heat supply technology, the cost for developing the hot dry rock well completion depth is too high, or the position of extraction equipment needs to be frequently replaced for a water source heat pump are solved. The exchange well comprises an excavated motor-pumped well, a well pipe, a circulating water pipeline and a permeable heat exchange layer arranged between the well pipe and the excavated motor-pumped well. The well pipe comprises a well mouth, a water return well pipe and a water intake well pipe; an isolating device is arranged between the water return well pipe and the water intake well pipe; the circulating water pipeline comprises a water taking pipeline and a water returning pipeline; the water return well pipe comprises at least one group of non-porous water return well pipe and water return floral pipe; the water taking well pipe comprises at least one group of water taking floral pipes and a hole-free water taking well pipe; the upper end of the water taking pipeline is connected with an inlet of the water pump; the lower end of the water taking pipeline is opened in the water taking well pipe; the upper end of the water return pipeline is connected with the heat pump unit outlet; the lower end of the water return pipeline penetrates through the isolation device and then is opened in the water return well pipe; the utility model also provides an exchange system.

Description

Technical Field

[0001] The utility model relates to a geothermal energy exchange well and an exchange system, in particular to a closed-circulation shallow geothermal energy exchange well and an exchange system. Background Art

[0002] Hot dry rock has a unique high temperature. If it is successfully mined, it will be a good heat source for winter heating. However, due to its high cost, it is difficult for ordinary people to afford the high cost of well construction for heating small buildings. Therefore, using hot dry rock technology for centralized heating is a more appropriate choice.

[0003] Dry hot rock heating technology is a technology that uses a drilling rig to drill holes into medium-high temperature rock layers at a depth of 2000 to 6000 meters underground, installs a closed or open metal heat exchanger in the hole, extracts heat energy from deep underground through a heat exchange medium, and directly heats ground buildings through a circulating pump system.

[0004] The development and utilization of hot dry rocks have advantages that are incomparable to other energy types in terms of protecting the atmospheric environment and resource reserves. Hot dry rock resources do not burn fossil fuels during their utilization, and therefore do not emit greenhouse gases such as carbon dioxide and other pollutants.

[0005] Hot dry rocks are abundant in reserves and can be recycled to meet the needs of long-term human use.

[0006] The technical principle of conventional water source heat pump is as follows: water source heat pump is a highly efficient, energy-saving and environmentally friendly air conditioning system that uses shallow underground geothermal resources for both heating and cooling. Water source heat pump can realize the transfer of energy from low-temperature heat source to high-temperature heat source by inputting a small amount of high-quality energy (electricity); in winter, heat is "taken" out of groundwater, and the temperature is raised before supplying it to indoor space for heating; in summer, heat is "taken" out of the indoor space and released into groundwater, and the groundwater temperature can be kept balanced all year round. It has the following advantages:

[0007] 1. Dry hot rock heating technology belongs to renewable energy utilization technology: water source heat pump is a heating and air conditioning system that uses shallow geothermal resources on the earth's surface (usually less than 100 / 200 meters deep underground aquifer groundwater) as a cold and heat source carrier to convert energy. Shallow geothermal resources on the surface can be called geothermal energy. It is not restricted by regions, resources, etc. It is truly large in quantity, wide in scope, and ubiquitous. This nearly unlimited renewable energy stored in the shallow surface makes geothermal energy also a form of clean renewable energy.

[0008] 2. Water source heat pump is an economical and effective energy-saving technology: the temperature of geothermal or shallow geothermal resources is relatively stable throughout the year, higher than the ambient air temperature in winter and lower than the ambient air temperature in summer. It is a good heat source for heat pumps and cold source for air conditioners. This temperature characteristic makes the water source heat pump 40% more efficient than the traditional air conditioning system, so it can save energy and operating costs by about 40%. Theoretically, the energy efficiency ratio can reach 7, and it can also reach 4-6 during operation due to factors such as circulating pumps. In addition, the relatively constant temperature of geothermal energy makes the operation of the heat pump unit more stable and reliable, and also ensures the efficiency and economy of the system.

[0009] 3. Water source heat pumps have significant environmental benefits: Compared with air source heat pumps, the carbon emissions of water source heat pumps are reduced by more than 40%, and compared with electric heating, they are reduced by more than 70%. If combined with other energy-saving measures, energy conservation and emission reduction will be more obvious.

[0010] Although it also uses refrigerant, it requires 25% less charge than conventional air conditioners. It is a self-contained system, which means that the device can be pre-assembled and sealed in the factory workshop, so the chance of refrigerant leakage is greatly reduced. The operation of the device is pollution-free and can be built in residential areas. There is no combustion, no smoke, no waste, no need for a site to store fuel waste, and no need to transport heat over long distances.

[0011] 4. Water source heat pump has multiple uses: wide application range. The water source heat pump system can provide heating, air conditioning, and domestic hot water. It has multiple uses. One system can replace the original two sets of devices or systems of boiler and air conditioning. It can be used in hotels, shopping malls, office buildings, schools and other buildings, and is more suitable for heating and air conditioning in villas.

[0012] 5. Low cost of use and maintenance of water source heat pump air conditioning system: Under the same conditions, buildings using water source heat pump system can reduce the cost of use and maintenance. Water source heat pump is very durable, it has very few mechanical moving parts, all parts are either buried underground or installed indoors, thus avoiding the harsh outdoor climate, its underground part can be guaranteed for 20-30 years, and the above-ground screw machine equipment can be guaranteed for more than 30 years, so water source heat pump is a partial maintenance-free air conditioning, saving maintenance costs, so that the user's investment can be recovered in about 5 / 8 years.

[0013] In addition, the service life of the valves in the external pipelines of the unit is more than 20 years, and the service life of the selected materials can be more than 30 years; the unit is compact and space-saving; the degree of automatic control is high and can be unmanned.

[0014] Of course, water source heat pumps are not perfect; the one-time investment and operating costs will vary from user to user; and the semi-closed recycling method of groundwater, in addition to the high cost of developing hot dry rock wells, the need to frequently change the location of the extraction equipment, and the large space required, is also restricted by the local groundwater resource management department due to the problem of reinjection water consumption.

[0015] Most of the existing hot dry rock heating technologies are to develop two wells, one for water extraction and the other for water return. The bottom is connected by water hammer or horizontal drilling rig, or a 2000-3000 meter blind well is drilled vertically, and heat is extracted by metal heat extraction blind pipes. Heat is extracted by circulating water in the blind pipe and repeated cycles, but due to the depth of the well, the cost of drilling and well completion is too high. The cost of a single well is about 3 million yuan, and the heating area is about 10,000 square meters. This semi- / fully closed recycling method has the problems of high cost of developing hot dry rock wells, large space required, long investment recovery period, and narrow industry survival space. Utility Model Content

[0016] The purpose of the utility model is to solve the problems of the existing hot dry rock heating technology, such as the high cost of developing hot dry rock wells, the need for frequent replacement of the extraction equipment of water source heat pumps, the imbalance of extraction / return water, the long investment recovery period, and the narrow industry survival space, thereby providing a closed-loop shallow geothermal energy exchange well and exchange system.

[0017] The thermodynamic principles on which the utility model is based are as follows:

[0018] The utility model is based on the law of increasing entropy, that is, in a closed isolated system (a system that has neither material exchange nor energy exchange with the outside world in thermodynamics), heat always flows from high temperature to low temperature, from order to disorder, and this process is irreversible. If there is no external intervention, the heat will gradually tend to chaos and disorder.

[0019] The utility model intervenes in low-temperature heat to improve its availability, and then performs earth heat exchange after heating to restore it to the temperature state before the heat pump intervention to continue the next cycle.

[0020] The concept of the utility model is as follows:

[0021] A well pipe is set in the excavated well and divided into two parts to obtain a water intake well pipe for taking water and a water return well pipe for returning water. A permeable heat exchange layer is filled between the excavated well and the well pipe. A closed circulation of water can be achieved through the unidirectional flow of water medium between the well pipe and the permeable heat exchange layer.

[0022] The water medium that has released its energy is transported by the heat pump unit to the return well pipe through the return pipe. The heat exchange cavity formed by the return well pipe and the permeable heat exchange layer (imitating the "artificial high-pressure fracture mode" in the deep well of hot dry rock) conducts effective heat exchange to complete the absorption, circulation and rise of energy; the water that has completed the heat exchange rises and enters the water intake well pipe, thus completing the process of water intake in a well, (releasing energy in the heat pump unit) return water, and heat exchange (energy absorption) between the permeable heat exchange layer and the earth.

[0023] In order to realize the above concept, the technical solution adopted by the utility model is:

[0024] A closed-circulation shallow geothermal energy exchange well, comprising a well excavation machine and a well pipe arranged in the well excavation machine, wherein the well excavation machine has a depth of no more than 800m and is within the most economical range of well construction cost, and the special features thereof are:

[0025] It also includes a circulating water pipeline arranged in the well pipe, and a water-permeable heat exchange layer arranged between the well pipe and the well excavator;

[0026] The well pipe comprises a wellhead, a return well pipe and a water intake well pipe; an isolation device is arranged between the return well pipe and the water intake well pipe; the return well pipe is located above or below the water intake well pipe;

[0027] The circulating water pipeline includes a water intake pipeline and a water return pipeline;

[0028] The return water well pipe includes at least one group of non-porous return water well pipes and return water flower pipes; the intake water well pipe includes at least one group of intake water flower pipes and non-porous intake water well pipes;

[0029] The upper end of the water intake pipe is connected to the inlet of the ground water pump; the lower end of the water intake pipe opens into the water intake well pipe;

[0030] The upper end of the return water pipe is connected to the outlet of the ground heat pump unit; the lower end of the return water pipe passes through the isolation device and opens into the return water well pipe.

[0031] Furthermore, the water permeable heat exchange layer is a gravel layer.

[0032] Furthermore, the effective heat exchange stroke is greater than or equal to 30 meters.

[0033] Furthermore, the water intake pipe is located above the water return pipe.

[0034] Furthermore, the isolation device is a sealing plate.

[0035] Furthermore, the water intake well pipe comprises a water intake flower pipe and a non-porous water intake well pipe coaxially arranged from top to bottom;

[0036] The return well pipe comprises a non-porous return well pipe and a return flower pipe coaxially arranged from top to bottom;

[0037] The non-porous return water well pipe is coaxially connected with the non-porous water intake well pipe;

[0038] The isolation device is arranged at the connection between the non-porous return water well pipe and the non-porous water intake well pipe.

[0039] Furthermore, the water well pipe is a composite pipe provided with two circulation channels, and one side of the lower part of the composite pipe is provided with a flower pipe structure, which is used to achieve the communication between the water permeable heat exchange layer and one of the circulation channels;

[0040] The return well pipe comprises a non-porous return well pipe and a return flower pipe coaxially arranged from top to bottom;

[0041] The lower end of the composite pipe is coaxially connected to the non-porous return well pipe. The connection between the composite pipe and the non-porous return well pipe blocks one of the flow channels through an isolation device and is used as a water intake well pipe; the other flow channel of the composite pipe is used to communicate with the return well pipe.

[0042] The present invention also proposes a closed-cycle shallow geothermal energy exchange system, which is special in that it includes:

[0043] Water pumping units, heat pump units and the above-mentioned closed-loop shallow geothermal energy exchange wells;

[0044] The water pump group includes a water pump and a water intake pipeline;

[0045] The upper end of the water intake pipe is connected to the inlet of the water pump, and the lower end is arranged in the water intake well pipe;

[0046] The water pump outlet is connected to the water inlet of the heat pump unit;

[0047] The water outlet of the heat pump unit is connected to the upper opening of the return water well pipe through a return water pipeline.

[0048] Beneficial effects of the utility model:

[0049] 1. In the utility model, two mutually isolated return well pipes, water intake well pipes, a permeable heat exchange layer and a heat pump unit are connected by a water pump to form a closed loop circuit in which the water medium flows in one direction. When the water medium flows in the closed loop circuit, it exchanges heat with the permeable heat exchange layer to realize closed-loop shallow geothermal energy exchange.

[0050] The utility model achieves the effect of both taking water and returning water in one excavated well, thereby realizing water balance. Compared with the original method of using two wells, the cost of well construction is reduced, the occupied land / space is small, a balanced closed circulation of groundwater can be realized, and the investment recovery period is short. It is suitable for large-scale promotion, and is particularly suitable for the heating and air-conditioning needs of buildings or building complexes.

[0051] 2. In the utility model, the two functions of water intake and water return are realized in one excavated well, thereby ensuring the balance of groundwater and overcoming the defect that the existing water source heat pump system cannot achieve complete and stable heat exchange circulating water return due to its working principle.

[0052] 3. In the utility model, by setting up a permeable heat exchange layer, the water medium can complete the cyclic heat exchange with the earth in a closed space, and the possibility of water resource pollution and water resource waste is eliminated in terms of working principle.

[0053] 4. In the utility model, the lower end of the water intake well pipe used for taking water and the lower end of the return well pipe used for returning water can be used as sedimentation tanks. When water flows out of the excavation well or flows into the excavation well, impurities carried in the water will fall into the sedimentation tank under the action of gravity, thereby filtering and collecting impurities in the water and improving the service life of the water pump and heat pump unit.

[0054] 5. In the utility model, after heat exchange, the rock / soil temperature may eventually drop to about 10°C, but the heat from the earth's core will reheat the rock / soil, and soon the excavated well will reach 16°C-18°C again, thus achieving sustainable utilization of the heat of hot dry rocks and periodic cycle heating.

[0055] 6. In the utility model, during the entire heat exchange process, no greenhouse gas is emitted, which is beneficial to environmental protection.

[0056] 7. The utility model solves the defects of conventional hot dry rock wells in the prior art, such as the high cost of the well depth, the unsuitability for smaller capacity occasions, and the inability to be used for refrigeration; it also solves the problem of waste of circulating water recharge and groundwater pollution caused by the inability of traditional heat pump units that also use groundwater for heat exchange to achieve complete and stable heat exchange due to their working principle, and can form a set of efficient and complete heating / cooling system with traditional heat pump units. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a structural schematic diagram of a closed-circulation shallow geothermal energy exchange well embodiment 1 of the utility model;

[0058] Figure 2 This is a partial structural schematic diagram of a closed-cycle shallow geothermal energy exchange well embodiment 3 of the utility model;

[0059] Figure 3 This is a schematic diagram of the connection structure of the composite pipe and the isolation device in the third embodiment of a closed-circulation shallow geothermal energy exchange well of the utility model;

[0060] Figure 4 This is a structural schematic diagram of a closed-circulation shallow geothermal energy exchange well embodiment 3 of the utility model;

[0061] Figure 5 This is a structural schematic diagram of a third embodiment of a closed-cycle shallow geothermal energy exchange system of the utility model;

[0062] In the figure, 1. return water pipe; 2. non-porous return water well pipe; 3. water intake pipe; 4. non-porous water intake well pipe; 5. isolation device; 6. permeable heat exchange layer; 7. excavation well; 8. composite pipe; 9. water intake pipeline; 10. return water pipeline; 11. water pump; 12. heat pump unit; 13. wellhead. DETAILED DESCRIPTION

[0063] Embodiment 1:

[0064] The utility model proposes a closed-circulation shallow geothermal energy exchange well, such as Figure 1 As shown, based on an excavated well 7 not exceeding 800m, it includes the excavated well 7 and a well pipe arranged in the excavated well 7, a circulating water pipeline arranged in the well pipe, and a gravel layer arranged between the well pipe and the excavated well 7, which is used as a water permeable heat exchange layer 6.

[0065] like Figure 1 As shown, the well pipe can be regarded as two wells (water intake well pipe and return well pipe) connected in series, forming a complete heat exchange cavity loop between the permeable heat exchange layer 6 and the low-temperature dry hot rock well, and the circulating water pipeline includes a water intake pipeline 9 and a return water pipeline 10. Specifically:

[0066] like Figure 1 As shown, the well pipe includes a wellhead 13, a return well pipe and a water intake well pipe which are coaxially connected in sequence from top to bottom. An isolation device 5 is provided at the connection between the return well pipe and the water intake well pipe, which is used as an isolation device to isolate the return well pipe and the water intake well pipe. Specifically, the water intake well pipe includes a water intake flower pipe 3 and a non-porous water intake well pipe 4 (no hole means no water permeable hole) which are connected in sequence from top to bottom. The return well pipe includes a non-porous return well pipe 2 and a return flower pipe 1 which are coaxially connected in sequence below the non-porous water intake well pipe 4. The isolation device 5 is provided on the non-porous water intake well pipe 4 and the non-porous return well pipe 2. One end of the return water pipe 10 passes through the wellhead 13 and the isolation device 5 in sequence and is placed in the non-porous return water well pipe 2. The lower end of the water intake pipe 9 is arranged at the water intake flower pipe 3. The upper end of the water intake pipe 9 is connected to the inlet of the ground water pump 11. The other end of the return water pipe 10 and the other end of the ground water pump 11 (outlet) are both connected to the heat pump unit 12. The well pipe, circulating water pipe, permeable heat exchange layer 6 and heat pump unit 12 are formed into a closed circulation loop through the water pump 11, so as to realize the closed circulation heat exchange between the water medium in the loop and the shallow geothermal energy in the permeable heat exchange layer 6.

[0067] The lower end of the return water pipe 1 is also used as a sedimentation tank. The distance between the return water pipe 1 and the water intake pipe 3 forms an effective heat exchange stroke, and the heat exchange stroke is greater than or equal to 30 meters.

[0068] The water permeable heat exchange layer 6 preferably uses gravel-type water permeable materials. Compared with other water permeable materials, natural gravel-type water permeable materials have better water permeability and will not pollute groundwater. Generally, the static temperature of the water permeable heat exchange layer 6 when no water circulation is performed is about 20-25°C, and the dynamic equilibrium water intake temperature when water circulation is performed is about 18-20°C.

[0069] The return water pipe 1 and the intake water pipe 3 may be in the same underground aquifer or in different aquifers. The aquifer only plays a role of osmotic balance because the well heat exchange water is in a closed state.

[0070] The service life of the water intake pipe 3 located on the upper layer can be extended by well washing and other methods. Since the heat pump unit 12 has its own sand removal device, the sand content in the water injected from the heat pump unit 12 into the return pipe 10 is not large. The optimal sand settling height of the return water pipe used in the sedimentation tank is not less than 15 meters.

[0071] The cross-sectional area of ​​the water-permeable heat exchange layer 6 is proportional to the water permeability effect, and the cross-sectional area of ​​the water-permeable heat exchange layer 6 can be adjusted according to actual needs. The water permeability and the heat exchange stroke determine the heat exchange capacity of the well.

[0072] The working principle of the utility model is as follows:

[0073] Water used as a heat exchange medium is extracted by a water pump 11, flows from the water intake well pipe into the external heat pump unit 12, and is reinjected into the ground through the return water well pipe after operation to form a closed cycle. After being injected into the ground, the groundwater exchanges heat with the earth during the process of rising along the return water well pipe and the gravel permeable layer 6 until it reaches the water intake flower pipe 3 along the well wall, and enters the water intake flower pipe 3, completing a heat exchange cycle and a reciprocating cycle.

[0074] The present invention also proposes a closed-cycle shallow geothermal energy exchange system based on the above structure, comprising a water pump unit, a heat pump unit 12 and the above closed-cycle shallow geothermal energy exchange well;

[0075] The water pump group includes a water pump 11 and a water intake pipeline 9;

[0076] One end of the return water pipe 10 passes through the wellhead 13 and the isolation device 5 in sequence and is placed in the non-porous return water well pipe 2. The lower end of the water intake pipe 9 is arranged in the water intake well pipe, and the upper end is connected to the ground water pump 11. The other end of the return water pipe 10 and the outlet of the water pump 11 are both connected to the heat pump unit 12.

[0077] After the water serving as the heat source is pumped by the water pump 11, it is transported from the water intake pipe 9 to the heat pump unit 12, and becomes cold water after operation. The cold water is re-injected into the ground through the return pipe 10 through the heat pump unit 12 to form a fully closed cycle. After the cold water is injected into the return well pipe, it exchanges heat with the earth and groundwater during the process of rising along the permeable heat exchange layer 6, until it enters the water intake well pipe through the water intake flower pipe 3 along the permeable heat exchange layer 6, completing a heat exchange cycle.

[0078] Embodiment 2:

[0079] The difference between Example 2 and Example 1 is that:

[0080] The water intake pipe in Example 1 is used for returning water, and the water return pipe is used for taking water.

[0081] Embodiment 3:

[0082] The difference between Example 3 and Example 1 is that:

[0083] like Figure 2 , Figure 4 and Figure 5 As shown, the water intake well pipe is a composite pipe 8 provided with two flow channels, and one side of the lower middle part of the composite pipe 8 is provided with a flower pipe structure for communicating with one of the flow channels; the upper end of the composite pipe 8 is used as a wellhead;

[0084] The return well pipe comprises a non-porous return well pipe 2 and a return flower pipe 1 which are coaxially arranged from top to bottom;

[0085] The lower end of the composite pipe 8 is coaxially connected to the non-porous return well pipe 2. Figure 3 As shown, the connection between the composite pipe 8 and the non-porous return well pipe 2 blocks one of the flow channels through the isolation device 5; the distance between the flower tube structure on the composite pipe 8 and the return flower tube 1 forms an effective heat exchange stroke.

[0086] After one end of the return water pipe 10 passes through the composite pipe 8, it is placed in one of the circulation channels, one end of the water intake pipe 9 passes through the composite pipe 8 and is placed in another circulation channel, and a water pump 11 is installed. The other end of the return water pipe 10 and the other end of the water intake pipe 9 are both connected to the heat pump unit 12. The well pipe, the permeable heat exchange layer 6 and the heat pump unit 12 form a closed circulation loop through the water pump 11, realizing the closed circulation heat exchange between the water medium in the loop and the shallow geothermal energy in the permeable heat exchange layer.

[0087] Embodiment 4:

[0088] The difference between Example 4 and Example 3 is that:

[0089] One of the circulation channels in Example 3 is used to set the water intake pipe 9, and the other circulation channel is used to set the water return pipe 10.

Claims

1. A closed-circulation shallow geothermal energy exchange well, comprising a well (7) and a well pipe arranged in the well (7), wherein the well depth of the well (7) does not exceed 800 m, and is characterized in that: It also includes a circulating water pipeline arranged in the well pipe, and a water permeable heat exchange layer (6) arranged between the well pipe and the drilling machine well (7); The well pipe comprises a wellhead (13), a return well pipe and a water intake well pipe; an isolation device (5) is arranged between the return well pipe and the water intake well pipe; the return well pipe is located above or below the water intake well pipe; The circulating water pipeline comprises a water intake pipeline (9) and a water return pipeline (10); The return water well pipe comprises at least one group of non-porous return water well pipes (2) and return water flower pipes (1); the intake water well pipe comprises at least one group of intake water flower pipes (3) and non-porous intake water well pipes (4); The upper end of the water intake pipe (9) is connected to the inlet of the ground water pump (11); the lower end of the water intake pipe (9) opens into the water intake well pipe; The upper end of the return water pipe (10) is connected to the outlet of the ground heat pump unit (12); the lower end of the return water pipe (10) passes through the isolation device (5) and opens into the return water well pipe.

2. A closed-cycle shallow geothermal energy exchange well according to claim 1, characterized in that: The water permeable heat exchange layer (6) is a gravel layer.

3. A closed-cycle shallow geothermal energy exchange well according to claim 2, characterized in that: The distance between the return water pipe (1) and the intake water pipe (3) forms an effective heat exchange stroke, and the effective heat exchange stroke is greater than or equal to 30 meters.

4. A closed-cycle shallow geothermal energy exchange well according to claim 3, characterized in that: The water intake well pipe is located above the water return well pipe.

5. A closed-cycle shallow geothermal energy exchange well according to claim 4, characterized in that: The isolation device (5) is a sealing plate.

6. A closed-cycle shallow geothermal energy exchange well according to any one of claims 1 to 5, characterized in that: The water intake well pipe comprises a water intake flower pipe (3) and a non-porous water intake well pipe (4) which are coaxially arranged from top to bottom; The return well pipe comprises a non-porous return well pipe (2) and a return flower pipe (1) which are coaxially arranged from top to bottom; The non-porous return water well pipe (2) is coaxially connected with the non-porous water intake well pipe (4); The isolation device (5) is arranged at the connection between the non-porous return water well pipe (2) and the non-porous water intake well pipe (4).

7. A closed-cycle shallow geothermal energy exchange well according to any one of claims 1 to 5, characterized in that: The water intake well pipe is a composite pipe (8) provided with two circulation channels, and one side of the lower part of the composite pipe (8) is provided with a flower pipe structure, which is used to achieve communication between the water permeable heat exchange layer (6) and one of the circulation channels; The return well pipe comprises a non-porous return well pipe (2) and a return flower pipe (1) which are coaxially arranged from top to bottom; The lower end of the composite pipe (8) is coaxially connected to the non-porous return well pipe (2); one of the flow channels at the connection between the composite pipe (8) and the non-porous return well pipe (2) is blocked by an isolation device (5) and used as a water intake well pipe; the other flow channel of the composite pipe (8) is used as a return well pipe.

8. A closed-cycle shallow geothermal energy exchange system, characterized in that: include: A water pump unit, a heat pump unit (12), and a closed-loop shallow geothermal energy exchange well as claimed in any one of claims 1 to 7; The water pump assembly comprises a water pump (11) and a water intake pipeline (9); The upper end of the water intake pipe (9) is connected to the inlet of the water pump (11), and the lower end is arranged in the water intake well pipe; The outlet of the water pump (11) is connected to the water inlet of the heat pump unit (12); The water outlet of the heat pump unit (12) is connected to the upper opening of the return water well pipe through a return water pipe (10).

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